Moist fuel burning furnace with dumping hearth



am 54 R- E SAMPSON MOI-ST FUEL BURNING FURNACE WITH DUMPING HEARTH FiledJan. l5, 1952 3 Sheets-Sheet l New E6, 3954 R. E. sAMPsoN 2,694,371

MOIST FUEL BURNING FURNACE WITH DUMPING HEARTH Filed Jan. l5, 1952 3Sheets-Sheet 2 INVENTOR. z'car 64722/3072.

Nov., E6, B954 a. E. sAMPsoN MOIST FUEL BURNING FURNACE WITH DUMPINGHEARTH 3 Sheets-Sheet 3 Filed Jan. l5, 1952 United States Patent() MISTFUEL BURNENG FURNACE WITH DUMPING HEARTH Richard E. Sampson, Detroit,Mich., assigner to Bigelow- Liptalr Corporation, Detroit', Mich., acorporation of Michigan Application .anuary 15, 1952, Serial No. 266,490

1l Claims. (Cl. 110-7) My invention relates to industrial furnaces and,in particular, to hearth floor or grate constructions for moist fuelburning furnaces, e. g., bagasse furnaces.

Many generations ago, the cane sugar industry dis covered that thefibrous refuse (bagasse) which remains after the cane is ground in theroller mills could be used as a fuel to produce steam for operating theequipment of the sugar mill. This was an important and valuablediscovery because most sugar mills were, and still are, situated wherefuel is difficult and expensive to obtain. Furthermore, it was theanswer to the problem of how to dispose of the bagasse, this being aproblem of no small proportions when it is realized that the individualmills grind from 100 to more than 2000 tons of cane a day during thegrinding season. As a consequence, much inventive effort has beendevoted to the development of furnaces that would burn this fuel in amanner which was satisfactory to the needs of the cane sugar industry.

It may be said that, in general, the primary consideration of theindustry in connection with these furnaces has not been efficiency ofcombustion, for in most instances there has been a surplus of bagasse,but continuity of operation. This general statement is subject toexceptions which, in recent years, are becoming more common whereinefficiency and cost of installation are also of prime importanceand inthese cases the invention of my copending application, Serial No.266,489, filed January l5, 1952, entitled Moist Fuel Burning Cell willbe ot' great interest. Continuous operation is important because of theseasonal nature of this industry. The grinding season lasts only a fewmonths of the year and during this period the mills run at top capacity,twenty-four hours a day. lf one of the furnaces is shut down forcleaning or repairs, there is loss of steam and, therefore, a loweringof capacity. In many cases, the mills have found it more economical tohave stand-by equipment and operators than to suffer this loss.

Though other methods are used, probably the most popular method ofburning bagasse is to pile it in a cell or primary combustion chamberwithin the furnace. Originally, the pile was supported on a gratethrough which combustion air was supplied and which could be actuated todump the ash and residue into a pit below. This proved to beunsatisfactory because the silica thrown into the furnace with thebagasse formed a slag at the high furnace temperatures that clogged thegrate so that air couldnt reach the bagasse in sufficient quantities.Furthermore, burning fuel dropped through the grate and burnedunderneath to rob the air supply and to overheat the grate. Thesedifficulties with the gratetype furnace substantially reduced boilercapacity and resulted in the development of the hearth or gratelessfurnace in current use. This furnace has a surrounding wall with a dooron one side and with air openings or tuyres in the wall so that a forceddraft can be supplied to sides of the pile of bagasse on the hearthinside the wall or cell. Gregory-Ward Patent No. 1,952,010 shows awidely used hearth cell design, the so-called Cook or horseshoe design,and one with which the present invention may be used, as illustratedhereinafter.

While this, the hearth type of furnace, is regarded by many as the bestdesign available, it has its drawbacks. From the standpoint ofcontinuous operation, a serious weakness of this type of furnace is thatit must be cleaned out every eight hours or so. In the past, this hasbeen done by opening the door in the hearth wall so that the operatorscould hoe out the ash and break formations. Considerable time wasconsumed since the furnace was quite hot and unpleasant for the workers.Furthermore, during at least the cleaning period, the furnace door wasopen and this admitted excess air that actually acted as a coolant toresult in still further loss of steam. Those in the art will be familiarwith other important drawbacks incident to the cleaning of this type offurnace, such as early destruction of base -masonry due to prodding inthe course of slag removal.

In overcoming these drawbacks, my invention makes it possible to clean afurnace of this type in only a matter of minutes, and the job islargely` mechanical rat-her than manual. I use a movable hearth floor orgrate ,to support the pile of moist fuel and which preferably tiltsupwardly about a horizontal axis adjacent the hearth door so that ashes,etc., are mechanically deposited at the door of the furnace throughwhich they can be quickly removed without first cooling down thefurnace. My tiltable floor fits close enough to the side wall of thehearth or cell so that it scrapes it as it is tilted, thereby removingslag and other material that may be clinging to it. The tiltable floorcan be installed in existing installations as well as in newinstallations; and, in order to insure its long life, l prefer to mountit in and at the top of a pit beneath the furnace which is incommunication with the forced draft furnished to the tuyres so that thefloor will be continuously cooled.

My invention is shown by way of illustration in the accompanyingdrawings, wherein:

Figure l is a vertical section through a portion of bagasse furnaceinstallation embodying a tiltable floor or grate constructed inaccordance with the invention;

Fig. 2 is a horizontal section taken along the line 2--2 of Fig. l;

Fig. 3 is a vertical section aken alongfthe line 3 3 of Fig. l;

Fig. 4 is a vertical section taken along the line 4;-4 of Fig. 3;

Fig. 5 is a vertical section of Fig. 3;

Fig. 6 is a vertical section taken along the line 6-6 of Fig. 2;

Fig. 7 is a section taken along the line 7 7 of Fig. 6; and

Fig. 8 is an enlarged view of the joint between the tiltable floor andfixed ledge.

The hearth lioor or dumping grate of this invention is shown in thedrawings in connection with improved features for a bagasse furnace suchas illustrated in my copending application, Serial No. 266,489, filedJanuary 15, 1952, entitled Moist Fuel Burning Cell, the specificationand drawings of which are incorporated herein by reference. Briefly,this type of furnace has preferably a hearth cell construction of theso-called Cook design; that is, it is ordinarily U- or horseshoe-shapesuch as illustrated best in Fig. 2. The major portion of the wall of thecell which, in accordance with the invention of said copendingapplication, is constructed of a series of horizontal courses formedfrom individual blocks of tile 3 which rest upon a lower course of castiron blocks S that are staggered in height. The various blocks andcourses are mechanically keyed together and forced laterally againsteach other and longitudinally against masonry pillars 6 at the front ofthe cell by means of U-shaped retaining bars 7 that fit in alignednotches 9 in each horizontal course of blocks, the ends of the barsbeing secured to the pillars 6 or to suitable posts or abutments at thefront of the furnace. The tile blocks 3, the cast iron blocks S, and thepillars 6 have suitable tuyres 11 whereby air under forced draft fromplenum chamber 13 which is furnished to the outside of the cell wall maypass through the wall to the inside of the cell, as described in moredetail in my copending apl plication. The air for this purpose issupplied by a blower or the like to the chamber 13 that is located atAthe rear of the cell 1. Gaseous products resulting from burning of thebagasse or other moist fuel in the cell rise through the throat 15 ofthe furnace and pass over the boiler tubes (not shown), it beingapparent to those taken along the line 5-5 off the slag,

in the art that the furnace of Fig. 1 is of the well-known Wardbottleneck design.

The moist fuel may be fed to the cell 1 by means of an inclined chute 17through which it slides by gravity to land on the hearth oor or grate 19of the cell. Preferably, a pair of Dutch doors 21 are provided at thefront of the furnace and constructed in accordance with the inventiondisclosed in the copending application of my co-worker, Robert A. Banck,Serial No. 314,901, led October 15, 1952, entitled Moist Fuel BurningFurnace Door Construction, which application is assigned to the sameparty as the present application. Those in the art will appreciate,however, that the invention may be used with cells having ordinary doorconstructions and, in fact, it is intended that the invention be capableof installation in existing furnaces. The doors are used to permit oper-{ators of the furnace to insert suitable pokers or hoes into the furnaceor to enter the furnace. The furnace has a masonry sill 23 immediatelyin front of the doors 21 and which is adjacent ground level or the levelof the oor 24 on which the operators stand. The sill 23 is also on a;level with or above the bottom of the lower of the doors 21 wherebymaterial on the sill may be easily shoveled or pulled out of the lowerdoor.

In accordance with the present invention, the hearth or grate 19 iscontoured to tit the inside of the wall of the cell 1, due regard beinghad to expansion, and is pivoted at its front end so that it may betilted about a horizontal pivot axis permitting its rear end to risewhereby material on the hearth will slide by gravity downwardly on tothe sill 23 from which it can be readily removed through the doors 21. Aparticular feature of importance is the fitting of the hearth plate orgrate 19 to the inside of the walls of the cell. This enables the hearth19, when tilted, to scrape the slag and other material clinging to thewall from the inside faces of the blocks 3 and 5 and eliminates themanual prodding that has been necessary heretofore.

While within the broad purview of this invention the hearth plate orgrate 19 may be constructed in various ways, it is preferably formed inthe manner illustrated in the drawings. Thus, it consists of leftandrighthand central castings 25 and 27 and leftand right-hand outercastings 29 and 31. These castings extend from the front to the rear,that is longitudinally, of the cell. They may be made from ordinary castiron, heat-resistant cast iron, cast steel, or other material, asdesired.

The central castings 25 and 27 have longitudinal downwardly extendinganges 33 formed on either side thereof and also transverse downwardlyextending flanges 35 at the front and rear. The innermost longitudinalsides of the outer castings 29 and 31 are also provided withlongitudinal downwardly extending flanges 34 which are counterparts ofand substantially identical to the anges 33. Suitable pads 37 are caston the flanges 33 and 34 and serve as areas of engagement among thevarious castings and are readily machined to give the proper t. Thehearth oor sections are bolted tightly together by transverselyextending bolts 38 that pass through aligned holes in the pads 37, asclearly seen from Fig. 3. The several hearth plate castings are formedwith suitable reinforcing ribs on the underside thereof in addition tothe anges which extend around them each peripherally. The reinforcingconstruction also includes a main and centrally located verticaltransversely extending reinforcement structure or keel 39 which includesa bottom horizontal flange 41. The keel and ange are made up of alignedsections cast in each of the component plates of the hearth floor 19.The flange 41 serves as a convenient attachment area for a hoor-liftingmeans. For such purpose, the bracket 43 is bolted to the flange 41 andincludes bifurcated portions that receive the end of the piston rod 45for a pressure fluid cylinder 47, a pivot pin 49 extending through theend of the rod and being journaled in and secured to the bracket 43.

The bottom of the cylinder 47 has bifurcated portions 51 which receive abracket 53 that is secured in position the bottom of a pit 55 below thehearth floor, the portion 51 and the bracket 53 being interconnected bya transverse pivot pin 54. It will be seen that the keel 39 reinforcesthe central area of the oor and that the cylinder 47 and rod 45 furnishsome measure of support also to the floor in the central areas thereof.The pit 55 preferably communicates, as shown in Fig. 1, with the airchamber 13 so that air draft from the chamber 13 can cool the hearthplates. Apertures 59 in the plates, as well as the clearances betweenthe anges 33 and 34 occasioned by engagement of pads 37, will enablesome air to reach the bottom of the pile of bagasse and, if this isrelied upon, it will be seen that these openings can be readily cleanedof slag or the like when the oor is tilted. Communication of the pit 55with the chamber 13 also provides a means of access to the pit wherebythe ash and other material which happened to drop into the pit may beperiodically cleaned out. The cylinder 47 is preferably an air-operatedunit but in any case will, of course, have the required circuit andcontrols such as fluid inlet and outlet connections 61 that pass throughsuitable control valves (not shown) and are connected to a suitablesource of uid pressure (not shown).

For the purpose of pivotally mounting the forward end of the hearthfloor 19, bifurcated brackets 63 may be bolted to the bottom of centralportions of the front ends of plates 29 and 31. The bifurcated portionsof these brackets receive brackets 65 that are secured to a ledge 67below and to the rear of the sill 23. Transverse pivot pins 69 pivotallyinterconnect the brackets 63 and 65. The rear edge of the hearth oor maybe supported on a ledge formed around the periphery of the cell by asuitable transversely extending angle bar 71 secured to the cell base72. The cutout sections 73 at the rear of the various hearth platesections tit on the bar 71. The supports for the hearth plate 19 arepreferably located so that the top of the hearth plate 19 is flush withthe sill and these two surfaces are preferably flush with the bottoms ofthe lowest course of blocks 5.

lt can now be readily seen that by applying pressure fluid to thecylinder 47, the piston rod 45 will be extended to pivot the hearth 19forwardly and upwardly about the axis of the pivot pins 69. As a result,the ash or other material on the hearth plate will slide onto the sill23 from which it can be readily removed through the doors 21. Duringthis movement of the hearth plate 19, it will scrape the cell wail toremove slag and other clinging materials. The sill 23 has a projectinglip 75 that remains close to the surface of the floor 19 when the latteris tilted to prevent material from sliding into the pit 55. The taperedinside faces of the pillars 6 tend to funnel the ashes toward the doors21 and thus facilitate their removal.

The invention thus makes it possible to quickly and thoroughly clean thefurnace with a minimum of manual labor and shut-down time and with aminimum admission of excess air. The fact that the tiltable oor is aircooled will tend to prevent sticking or adherence of ash and slag andtherefore facilitate their removal through the doors. It will beappreciated that the invention comprehends within its scope variousmodifications of the detail structure herein illustrated. It is,therefore, evident that the invention is not limited to the precisedetails of construction shown herein.

I claim:

1. In a moist fuel burning furnace comprising side wall means dening amoist fuel cell, the combination of a door in said side wall means, asill in the cell adjacent the lower side of the door, a movable floor inthe cell, said floor being pivoted on a horizontal axis at the edgethereof adjacent said sill, said axis being substantially parallel tothe plane of said door so that upon upward movement of the oor aboutsaid axis material on the oor will slide downwardly on to the sill, andmeans operatively associated with the floor for moving the floorupwardly about said pivot axis.

2. The invention set forth in claim l wherein said oor tits closelyenough to said side wall means so that upon upward movement thereof itfunctions as a scraper for the side wall means.

3. The invention set forth in claim 1 including a support for the edgeof the oor remote from said sill arranged to allow the oor to restthereon in a level position ush with the sill.

4. The invention set forth in claim 3 wherein said moving means for thefloor is power operated.

5. The invention set forth in claim 4 including means defining a pitbelow said oor, said power operated moving means comprising a pressureuid cylinder and piston device disposed in said pit and operativelyconnected to the oor.

6. The invention set forth in claim 5 including means associated withsaid pit for supplying air thereto to cool the oor, said pressure uidcylinder and piston device being connected to a central area of thefloor and serving as a support therefor.

7. The invention set forth in claim 6 including means providing a ledgebelow the top surface of the sill and at the edge of the sill adjacentsaid floor, said `floor being pivoted on transversely spaced and alignedpivot brackets located on said ledge, said brackets delining said pivotaxis and said axis being located below the top surface of the sill andspaced slightly from the edge of the door adjacent said sill so thatsaid edge and a portion of said oor projects over the pivot axis towardthe sill, said sill including a lip projecting from the top surfacethereof over said ledge and toward the floor and to a position closelyadjacent to said door edge, the sill being recessed away from the floorbeneath said lip to permit tilting of said floor portion and iioor edgebeneath said lip while preventing substantial clearance between thesurface of the ioor and the sill.

8. The invention set forth in claim 7 wherein said floor fits closelyenough to said side wall means so that upon upward movement thereof itfunctions as a scraper of the side wall means.

9. In a moist fuel burning furnace, side wall means defning a moist fuelcell, a door in said side wall means, a movable floor in the celldefining a substantially horizontal moist fuel supporting surfacecovering a major part of the area of the cell, said oor beingsubstantially impervious to the passage therethrough of moist fuel andits ash, said floor having a rst end adjacent said door and a second endremote from said door, means mounting said lioor for angular movement toa dumping position in which the first end is substantially on a levelwith the bottom edge of said door and the second end is substantiallyhigher than the first end so that said surface is on an angle to thehorizontal and material thereon will tend to slide downwardly toward thefirst end and thus said door, and means operatively associated with saidoor for moving said floor to said dumping position.

10. The invention set forth in claim 9 wherein the oor iits closely tosaid side wall means and upon movement thereof to said dumping positionfunctions as a scraper for the side wall means.

1l. The invention set forth in claim 9 including means defining a pitbelow said oor, said floor moving means comprising a power operatedmember mounted in said pit and operatively connected to a central areaof said floor and serving as a support for the oor as well as a meansfor moving the lioor to dumping position.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 140,155 Moore June 24, 1873 575,324 Boudreaux Jan. 19, 18971,860,841 McEver May 31, 1932 1,952,227 Adams Mar. 27, 1934 2,216,287Agar Oct. 1, 1940 2,524,868 Worsham Oct. 10, 1950 FOREIGN PATENTS NumberCountry Date 404,714 Germany Oct. 24, 1924 430,834 Great Britain June26, 1935

